Collapsible mine prop



J. L. KNIGHT COLLAPSIBLE MINE PROP Filed May 14, 1937 2 Sheets-Sheet 1 Jesse? L SLWM,

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Hgihl! l 1! 4W a: f 8 a 1% Z. w /Q 6 me A Oct. 10, 1939 J. L. KNIGHT COLLAPSliBLE MINE PROP Filed May 14, 1937 2 Sheets-Sheet 2 Patented Oct. 10, 1939 iATENT: OFFICE COLLAPSIBLE MINE PROP Jesse L. Knight, Powelltcn, W. Va., assignor of one-half to C. It. Stahl, Powellton, W. Va.

Application May I l, 1937, Serial No. 142,711

6 Claims.

The invention relates generally to mine props and primarily seeks to provide a novel form of prop, or jack as they are sometimes called, which is simple and durable in construction, capable of sustaining enormous loads without danger of failure, and capable of being collapsed safely and with a minimum of effort.

I am aware that collapsible mine props have heretofore been provided, but my years of experience with such of them as have been worthy of production commercially have proven that they are incapable of safely supporting enormous loads which must at times be supported, and that they cannot safely be collapsed under all conditions of use. Because of these defects the devices now known to the mining industry do not enjoy the full confidence of the miners who must depend upon them during their hours of toil.

One type of prop found objectionable is the type employing superposed column sections having opposed metallic end portions bearing angular relation to the vertical axis of the prop and intended to cause the sections to slide apart when freed to facilitate withdrawal of the prop from theload supporting position. In this form of prop, when the angle of the opposed surfaces is made too great, too great a lateral force component is set up, and even under relatively light loads the securing devices cannot stand the strain and breakage occurs. If the angle of the surfaces is made shallow the frictional resistance under heavy load becomes so great that the parts gall, as is said in the mines, or stick, and safe withdrawal of the prop is rendered impossible. Other forms of props include column portions filled with large masses of sand or gravel and valves or plugs for permitting leakage thereof when it is desired to collapse the props. This type of prop is objectionable because of the time consumed in retaining them properly supplied with the sand or gravel, they are subject to breakage under relatively light loads due to lateral force components, and they permit too much compression and length reduction for practical use in shallow veins, often thirty inches or less in depth. My invention seeks to remedy these defects.

In its more detailed nature the invention resides in the provision of a prop comprising superposed supporting column sections, a releasable wrapper encasing the opposed ends of the sections, and a mass interposed between the section ends and within the wrapper and which is free to fall out when the wrapper is released to bring about a collapsing of the prop.

Another object of the invention is to provide a mine prop including a split section adapted to facilitate collapsing of the prop.

Another object of the invention is to so shape the opposed ends of the prop sections as to com- 5 press the mass between them in the wrapper and subject the wrapper to a minimum of lateral strain.

Another object of the invention is to provide a novel construction and arrangement of the wrapper.

With these and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a side elevation illustrating the invention in use.

Figure 2 is a horizontal section taken on the line 2-2 on Figure 1.

Figure 3 is a horizontal section taken on the line 33 on Figure 1.

Figures 4 and 5 are enlarged vertical longitudinal sections illustrating the prop in operative and collapsing conditions respectively.

Figure 6 is a detail perspective view of the half of the. split. prop section which carries the wrapper.

Figure 7 is a detail perspective view of the separable half of the split prop section.

Like reference numerals designate corresponding parts throughout the several figures of the drawings.

In the practical development of the invention, we provide a metallic base plate 5 which is in the form of a flat disc havingaconcaved seat or socket 6 formed in the upper surface thereof to receive the mine prop.

The mine prop is composed of two superposed sections which together form a supporting column. The column is of generally cylindrical form and its diameter is to be determined by the maximum weight necessary to be supported on the props. The lower prop section is composed of two half pieces 1 formed by dividing the cylindrical whole at the plane of the axis, thus providing fiat opposing faces 8. At their lower extremities the opposed faces are beveled or cleared as at 9 so as to form a V-shaped recess or clearance between them as shown in Fig. 4 of the drawings, and the lower extremity of the prop section conjointly formed by the halves l is convexly shaped as at l 0 to fit the concavity 6 of the base. See Figs. 4 and 5.

The upper ends of the half members I are shaped to conjointly form a conoidal seat or recess II, and in this particular disclosure, one of said half members carries a socket-forming wrapper or sleeve member. It will be obvious, however, that the socket-forming wrapper can be formed as a separate element if desired.

The wrapper is in the form of a cylindrical sleeve and is composed of two half sections I2 and I3 hinged together as at M, the section l2 being formed integrally with one of the half members 1 or secured thereto in any suitable man ner, as by welding, as indicated at l5.

Each wrapper half is provided with a lug extension l6, and one of the lugs includes a toggle lock recess ll engageable with a lock dog l8 pivotally mounted as at l9 between link members 20 which are in turn pivoted as at 2| to the other of the lugs 16.

A lever arm 22 extends from the lock dog 18, and by manipulation of this lever the parts may be moved to the open condition illustrated in Fig. 6 of the drawings, or to the wrapper closed or locked condition as illustrated in Fig. 2. It will be observed by reference to Fig. 2 that when the parts are in the locked condition the lock dog pivot I9 will be past dead center so as to lock the parts against inadvertent release.

Should it be desired to positively lock the parts against inadvertent release so as to positively augment the positive lock, the lever extension may be equipped with an apertured ear 23 for registering, in the locked position, with an apertured ear 24 projecting from the wrapper half, and a safety pin 25 may be inserted through the registering apertures to positively lock the parts in the positions shown in Figs. 1 and 2 of the drawings. When the wrapper is in the closed condition shown in Figs. 1, 2 and 4 of the drawings, it forms a socket 26 above the lower prop section comprising the half portions 1, l. The lower end of the upper prop section 21 is receivable in the socket thus formed, and this upper section is provided at its lower end with a conoidal seat or depression 28 for opposing the similar seat formed in the lower prop section and is provided at its upper end with a head plate 29. It is to be understood that the upper prop section 21 may vary in length according to the dimen sions of the vein or mine opening in which the props are to be used. It is preferred that the upper and lower prop sections be formed of generally solid metal parts but it is to be understood that if adjustments are desired any of the conventional form of screw extensions may be employed.

When my improved props are to be put into use the plates are positioned on the mine floor or on any suitable supporting block and the lower, composite prop section seated thereon. The wrapper is closed by swinging the hinged halves thereof together and applying the toggle look as shown, and, if desired, the safety pin also, as shown in Fig. l of the drawings. A quantity of coal is then poured into the wrapper socket 2G and the lower end of the upper prop section is inserted into the socket on top of the coal mass 30 thus completing the assembly of the prop. Thereafter wedge blocks 3| are applied between the prop head plate 29 and the roof or overhanging wall and are driven together to secure the prop in place for suitably supporting the load imposed thereon.

When the load is imposed upon the prop the: coal mass is compacted as shown in Fig. 4 of the drawings so that the upper and lower prop sections are separated to an extent approximating an inch or less. By shaping the ends of the prop sections as shown, a minimum of lateral load component is exerted against the wrapper walls and thus a minimum of breaking strain is exerted against the wrapper.

If desired masses other than coal may be in terposed between the prop ends and we have experimented with wooden blocks of a diameter slightly less than the internal diameter of the wrapper with considerable success. These blocks need not be shaped at their ends to fit the section sockets H and 28 since the compressive strains will serve to conform the ends of the insert or core 30 and support the load over the entirety of the opposed surfaces.

When it is desired to collapse the prop the safety pin 25 is first removed and then the lever 22 is moved to break the toggle lock and allow the wrapper section l3 to move to the open position under pressure exerted by the supported load. As the wrapper opens and the upper prop section 21 moves downwardly, the core 30 will quickly be displaced, disintegrating in the case of coal or like mass.

As the load is thus quickly released movement of the core 30 and the upper prop section 21 will force the free lower prop section 1 away from its companion section as shown in Fig. 5 of the drawings and thus facilitate the collapse of the prop. The relative movement between the lower prop section l is facilitated by the curvature of the lower ends of the parts I and of the plate seat 6, and also by the beveling of the lower end faces 9 of said section parts.

The several parts comprising the prop preferably are permanently attached by connecting chains 32. The base 5 and the separable lower section part 1 both are connected to the wrapper by chains and the upper prop section 2'! is similarly connected to the wrapper by a chain, suitable slack being provided for permitting necessary manipulation of the parts. The safety pin may also be attached to the wrapper by a chain.

It is to be understood that the angles of the walls forming the prop section recesses H and 28 may be varied in different sizes of props. In this illustration, I have proportioned the prop to be particularly adaptable in shallow vein mining when the coal seam approximates thirty inches in depth. In this proportioning the shaft sections may be two inches in diameter. The walls defining the lower section recess II preferably are disposed at an angle of 20 and those defining the upper section recess 28 at an angle of 25. I find it preferable to always form the walls of the upper section at a greater angle than those of the lower section. It is possible also to form the lower extremity of the upper section without any recess but it is preferred that both sections be recessed at the opposing ends as hereinbefore described.

In the foregoing description I have disclosed a simple and efiicientform of mine prop capable of sustaining enormous loads and which is so constructed as to permit collapsing thereof with a minimum of effort and in absolute safety. No metal to metal contacts are provided which might gall or stick when it is intended to collapse the prop. The use of the safety pin and lug equipment 25, 25, 21 are not entirely necessary in view of the toggle lock provided. These safety parts may, however, be employed to positively prevent inadvertent collapsing of the prop and if desired the toggle lock lever 22 may be equipped with a chain connection by which it may be tripped from a safe distance.

It is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and scope of my invention.

I claim:

1. In a mine prop, upper and lower supporting sections disposed in end to end relation, a releasable wrapper encasing the opposed ends, and a fall out mass disposed between and normally separating said ends and releasable upon release of said wrapper to cause a collapsing of said sections, one said supporting section having a concave face in the end thereof opposed to the other supporting section end and being formed of separable half portions to facilitate collapsing of the prop.

2. In a mine prop, upper and lower supporting sections disposed in end to end relation, a releasable wrapper encasing the opposed ends, a fall out mass disposed between and normally separating said ends and releasable upon release of said wrapper to cause a collapsing of said sections, one said supporting section having a concave face in the end thereof opposed to the other supporting section end and being formed of separable half portions conjointly forming a convex seating extremity, and a rest plate having a concave seat to receive said seating end.

3. In a mine prop, upper and lower cylindrical supporting sections disposed in end to end relation, a. releasable wrapper encasing the opposed ends, a fall out mass disposed between and normally separating said ends and releasable upon release of said wrapper to cause a collapsing of said sections, one said supporting section. having a concave face in the end thereof opposed to the other supporting section end and being divided along its axis to form separable half cylindrical portions and shaped to conjointly form a convex seating extremity, and a rest plate having a concave seat to receive said seating end,

4. In a mine prop, upper and lower cylindrical supporting sections disposed in end to end relation, a releasable wrapper encasing the opposed ends, a fall out mass disposed between and normally separating said ends and releasable upon release of said wrapper to cause a collapsing of said sections, one said supporting section having a concave face in the end thereof opposed to the other supporting section end and being divided along its axis to form separable half cylindrical portions and shaped to conjointly form a convex seating extremity, and a rest plate having a concave seat to receive said seating end, said wrapper comprising a cylindrical sleeve composed of hinged sections and a toggle lock for releasably securing the sleeve sections together.

5. In a mine prop, upper and lower supporting sections disposed in end to end relation, a releasable wrapper encasing the opposed ends, and a granular mass disposed between and normally separating said ends and releasable upon release of said wrapper to cause a collapsing of said sections, said opposed ends having conoidal recesses therein and said wrapper comprising a sleeve composed of hinged sections and a toggle lock for releasably securing the sleeve sections together.

6. In a mine prop, upper and lower cylindrical sections disposed in end to end relation, a releasable wrapper encasing the opposed ends, a granular mass disposed between and normally separating said ends and releasable upon release of said wrapper, one said supporting section having a concave face in the end thereof opposed to the other supporting section end and being divided along its axis to form separable half cylindrical portions and shaped to conjointly form a convex seating extremity, and a rest plate having a convex seat to receive said seating end, said wrapper comprising a cylindrical sleeve composed of hinged sections and a toggle lock for releasably securing the sleeve sections together, and one said hinged section being secured to and carried by one said separable half portion.

JESSE? L. KNIGHT. 

